Maybe you need to phone to microsoft when you install it on another one to
active your copy of Halo . This should be work as same with the vista
activation .
P.S I do not own Halo, so it is for reference only..
Yes Dan, you can. I have Halo 2, I installed and activated it on a machine,
uninstalled it and installed it on another and it re-activated, no call
necessary, but don't be suprised if you have to call a 1-800 number to get
your game running again.